Jargondictionary says they mean. They have different meanings to the people using them than their everyday meaning.
For example, the ordinary words boot, net and web also have special meanings for users of computers, the Internet and the World Wide Web. These, and to flame, to ping and many acronyms are part of net jargon. See separate article on this.
An acronym means that only some of the letters in the word or phrase are used. Often this is the first letter of each word. Other acronyms found online are simply common shorthand. See List Of Slang Words
Usually, more jargon is created over time.
Jargon is also common in the military. It includes phrases like SNAFU and shit sandwich.
Jargon can be used by a clique to prevent others from joining or understanding, but it also is often just used because it is shorter.
See also: idiom